re: What is the worst mainstream movie you've ever seen?

Five immediately come to mind:

Suicide Squad, for the obvious. Unforgivable. Never forget.

Some stupid arse pos movie starring Pierce Brosnan, Salma Hayek, and Woody Harrelson. I don't even remember the title, only that it was fricking awful, a dumb boring plot, and riddled with clumsy cliched dialogue. "Let's do this" was used like 5x.

Batman & Robin, for the obvious. Unanimously agreed upon as one of the worst movies ever made by humans. Schumacher deserved to be garrotted for making that crap, but then he apologized for making it so I no longer feel revenge, only pity.

Funny People. The people were not funny at all and were pieces of shite on top. In fact, I hated them all and found myself wishing them dead. I rooted for the cancer with Adam Sandler's character. Horrible, dumb, pointless plot with despicable characters that were not funny.

No Strings Attached. I love Natalie Portman but not even she could stop me from hating this terrible movie. Dumb, boring, meaningless plot littered with characters that I could not care less if they lived or died. A father character trying so hard to be funny and failing. An annoying Mindy Kaling. The best thing about the movie was Ashton Kutcher. That says it all.